This disclosure relates to apparatus for holding a cutting bit used to cut earth, rock, pavement and the like and, in particular, to an improved cutting bit holding apparatus.
In the mining field and in other fields in which a large volume of hard materials must be cut, it is typical to employ an apparatus which includes a vertically moveable horizontal axis cutting drum having cutting bits attached thereto. By virtue of the engagement of the cutting bits, which are mounted on the rotating cutting drum, with the surface to be cut, material is removed from such surface for further processing.
Due to the substantial forces generated during the cutting operations, the cutting bits must be securely mounted on the cutting drums, and must also be readily removable for replacement. In one prior art form of cutting bit holding apparatus, a cutting bit having an elongated cylindrical shank and a hard cutting tip at one end, and an abutment surface at the other end, is retained in a bit holder which is usually welded to the cutting drum. Such bit holder includes a body portion having a forward surface (as taken in the cutting direction) and a rearward surface. A shank receiving bore extends through the body and forms openings in the forward and rearward surfaces for passage of the shank of the cutting bit there through.
Illustrated in FIG. 1 is shown a conventional cutting bit holder 10 which is mounted on a cutting drum 14 which is rotatable in the direction shown by arrow 16. Specifically, bit holder 10 is mounted as by welding on a riser block 18 that is mounted, also as by welding to the cutting drum 14. However, it will be appreciated that the bit holder 10 may be mounted directly on the cutting drum 14.
More particularly, as shown in FIGS. 2 and 3, a conventional bit assembly 13 comprises a bit 12 having a bit tip 24, and a bit sleeve 25. The bit sleeve 25 includes a holding portion adapted to receive the bit 12, and a bore through the holding portion. The bit assembly 13 also includes an ignition control unit 30 including a spray outlet 34 having an internal bore (not shown). In other embodiments, sleeveless bit assemblies (not shown) can be used.
The bit assembly 13 also includes a bit holder 40 including a mounting base, and means for releasably securing the ignition control unit 30 to the rear portion in the form of a retainer or clip 42. The mounting base has a forward portion 44 and a mounting base rear portion 48.
The mounting base forward portion 44 has an upwardly open socket 52 adapted to receive the bit sleeve 25 so that the bit tip 24 extends in a forward direction, and an opening 56 to the interior end of the upwardly open socket to assist in removal of the bit sleeve 25. The mounting base rear portion 48 has an upper opening 60 that receives the ignition control unit 30, and an internal water passageway 64 in communication with the upper opening 60. The base rear portion 48 also has an external grove 68 in communication with a drum internal passageway 72 in the drum 11. As is known in the art, a fluid such as water within the drum 11 flows out of the drum passageway 72, through the drum external groove 68, and then through the internal water passageway 64 to the upper opening 60. From there, the water passes through the ignition control unit 30, where the water is then sprayed on the surface being mined.